Re: Opinions on this Chopper drive schematic?

I'm counting on hitting resonance problems actually. My purpose in
rolling my own isn't to save money, its to learn how everything
works. Personal education is the main reason for doing any of this.
Secondary reason is to have a kick-arse super accurate mill/drill.

I plan on building at least three units.

#1 will be a piece of crap - 1/4-20 leadscrews, backlash out the ying
yang, trammeling that truly sucks - you name a problem, I'll have
it :D The point here is to be CHEAP because its all throw away. I
want to make the biggest mistakes on the cheapest setup. This is what
the aformentioned chopper drive will be used on. Hopefully (after
much re-working) I'll be able to use this to make some of the parts
for...

#2 - I'll purchase and use the final motors and precision parts (acme
screws etc) on this one. I'll try to do a much better job of it,
incorporating all the lessons from #1 While the precision parts will
be expensive, I'll be using cheaper materials for the rest of it.
After seeing how the "primitive" chopper drive works and learning a
bunch more, I'll make a second driver board incorporating the
changes. When this is working as well as possible I'll use it to make
parts for...

#3 - The expensive one. I should have enough experience by this time
to build a unit that will actually perform as I require. This is
where I blow the big bucks for the most efficient materials (not "The
Best"). I'll decide whether I need a new driver board and better
motors etc at this time.

Timeframe for the above? No idea... It'll take as long as it takes.
Cost? same thing :D

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
>
>
> ghidera2000 wrote:
>
> >Found a PDF with a nice clear description of how to build a
chopper
> >drive circuit. http://www.kevinro.com/chpdrv.pdf.
> >
> >Anything bad about this one or a feature missing that you'd
consider
> >fairly important?
> >
> >I know I can buy drivers from Gecko etc (probably for less money
in
> >the end-game), but thats not the point. Its a hobby, I'm supposed
to
> >blow money, break parts, and have a good time :D
> >
> >
> This is a 2 A 40 V full- or half-step driver. Pretty primitive.
>
> The Gecko 201A drive is a microstepping, 7 A, 80 V drive with
optoisolated
> inputs. The Gecko 210 adds pulse multiplying, in case your
computer can't
> output step pulses fast enough. It has electronic damping of
midband
> resonance, which is worth a LOT. You won't have resonance issues
> with the Gecko drive. A half-step drive will likely have resonance
> problems at some speeds.
>
> Jon